ニペソツ・丸山火山群

The Nipesotsu-Maruyama volcano group, located west of Nukabira Lake about 20 km E of Tokachidake volcano, is composed of a number of overlapping andesitic-to-rhyolitic stratovolcanoes and lava domes constructed along a NW-SE trend. These volcanoes overlap the SW rim and SW caldera floor of the Pleistocene Tokachimitsumata caldera. The highest peak in the complex is Nipesotsuyama stratovolcano, which was active during the mid-Pleistocene, about 0.4-0.2 million years ago. The Maruyama stratovolcano and lava dome at the southern end of the complex was discovered to be a Quaternary volcano only in 1989. It is also referred to as Higashi-Tokachi-Maruyama to distinguish it from several other volcanoes named Maruyama, which means "Round Mountain." A minor phreatic eruption took place at the Maruyama lava dome in 1898, and fumaroles are present on one of its summit craters.